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17 - Gaseous exchange
- from Part IV - The integument, gas exchange and homeostasis
- R. F. Chapman
- Edited by Stephen J. Simpson, University of Sydney, Angela E. Douglas, Cornell University, New York
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- Book:
- The Insects
- Published online:
- 05 December 2012
- Print publication:
- 12 November 2012, pp 501-545
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- Chapter
- Export citation
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Summary
Introduction
Gaseous exchange in insects occurs through a system of air-filled internal tubes, the tracheal system, the finer branches of which extend to all parts of the body and may become functionally intracellular in muscle fibers. Thus oxygen is carried in the gas phase directly to its sites of utilization. While the blood is not concerned with oxygen transport in most insects, some insects have now been shown to have hemocyanin, an oxygen-carrying pigment, in the blood. In terrestrial insects and some aquatic species, the tracheae open to the outside through segmental pores, the spiracles, which generally have some filter structures and a closing mechanism reducing water loss from the respiratory surfaces. Other aquatic species have no functional spiracles, and gaseous exchange with the water involves arrays of tracheae close beneath the surface of thin, permeable cuticle.
This chapter is divided into ten sections. Section 17.1 describes the tracheal system, its structure, distribution and development. Section 17.2 deals with the number, structure and distribution of the spiracles. Section 17.3 follows with cutaneous gas exchange; Section 17.4 treats respiratory pigments; and Section 17.5 describes gaseous exchange in terrestrial insects, considering diffusion and ventilation in resting and flying insects and control of ventilation. Section 17.6 addresses the gaseous exchange in aquatic insects, with oxygen uptake from the air and by gills. Section 17.7 gives attention to insects subject to occasional submersion. Section 17.8 refers to the gas exchange in endoparasitic insects. Section 17.9 is concerned with other functions of the tracheal system, and Section 17.10 with gas exchange in insect eggs.